This application relates to a rice processing apparatus engineered to stablize the formation of free fatty acids in rice bran, and thereby, permit the extraction of edible oil and the processing of the remaining defatted rice bran into edible food products.
Rice is the most widely comsumed cereal in the world. Although rice is abundantly grown throughout the world, the processing of the collected rice has created a vast resource which is going to waste. The most nutritious part of the rice is polished off the grain during the milling process. One of the most nutritious foods known to man however starts to become rancid in a matter of minutes after the milling process, rendering it inedible to humans, and after several days, indigestible to animals. As a result, a tremendous demand has been created for an apparatus and a technology to stablize the rice bran, thus allowing the necessry time to: (1) extract the oil, and (2) utilize the remaining defatted rice bran as a high protein, low fat cereal food for human consumption.
The processing method and apparatus should, of course, be such as to maintain the maximum nutrients in the final cereal product, while permitting effective and relatively rapid processing. Further, it is essential that the apparatus and method be adaptable for use in environments of lesser developed countries. Optimally, the unit should be a relatively compact, self-contained unit, engineered and constructed to allow for ease of movement to various remote processing locations. This will permit the processing of the rice bran without the necessity for having to immediately transport the rice bran to a central processing location for stablization and/or extraction. It is also imperative that the equipment be simple to operate and low in cost to permit the economic stbilization of the rice bran without the necessity of making large capital investments.
After the hull is removed from the rice, approximately 6 to 8% of the brown rice kernal is polished, yielding white rice and a by-product, rice bran. During the milling process, lipase, a highly active enzyme, is released. Within minutes, the lipase reacts with oil in the rice bran, resulting in a very rapid hydrolysis of the oil into free fatty acids (F.F.A.) making the bran unfit for human consumption. Within one day, it is no longer economically feasible to extract oil from the rice bran, and after three days, it is no longer possible to use the bran as a feed for animals due to the rancidity of the oil.
Various methods of inhibiting the growth and stabilizing the F.F.A. level in the rice bran is found in the literature, including the heating of the bran product and reference therefore may be made to an article by Williams in the Journal of Oil Chem., Soc. 42, 151 (1965).
Although various bran processing systems have been suggested, the prior art has to the knowledge of the inventor completely failed to include any teaching of an apparatus and/or method for proper processing of rice bran to establish a suitable rice bran product which retains essentially all of the nutrients in a practical, low-cost method and apparatus particularly for use in lesser developed countries.
For example, U.S. Pat. No. 4,465,477 which is entitled "Apparatus for Continuously Extruding and Drying/Cooling Cereal Bran", issued Aug. 14, 1984, discloses a large and bulky rice bran extruder for treating of bran to stabilize the bran product, and which would be primarily usable in association only with very large white rice processing plants.
Soybean processing equipment has also been developed for heating and processing of raw and untreated soybeans in such a manner as to cook the soybean for removal of a heat libile growth inhibiting material. For example, U.S. Pat. Nos. 3,685,429 and 3,685,430 to McBride and 3,695,891 and 3,765,319 to Fox all similarly disclose soybean processing equipment and methods specifically directed to the treating of raw and unprocessed soybeans by an expression process in which the raw soybean is extruded to heat the soybean. In particular, raw untreated soybeans are passed through the extruder and the soybeans are heated as a result of the extrusion process. As the extruded soybean is released, it emits the libile inhibiting material in the released moisture. The discharge end structure is an adjustable extrusion cone to control termperature and pressure as the soybeans are extruded. Such apparatus cannot be applied to rice bran processing because of different characteristics of rice bran and the generally different considerations encountered in the processing of the products.